Serving base station update in subsequent cell switch

Abstract

A first base station comprises one or more processors and memory storing instructions that, when executed by the one or more processors, cause the first base station to receive, from a second base station, a cell switch notification message, for a wireless device, comprising an identifier of a candidate cell. The instructions further cause the first base station to transmit, to a third base station, a second message to establish a connection, for the wireless device, between the first base station and the third base station. The second message comprises a first identifier identifying the wireless device within the first base station. The instructions further cause the first base station to receive, from the third base station, a third message, to establish the connection, comprising a fourth identifier identifying the wireless device within the third base station.

What is claimed is: 
     
         1 . A first base station comprising:
 one or more processors; and   memory storing instructions that, when executed by the one or more processors, cause the first base station to:
 receive, from a second base station, a cell switch notification message, for a wireless device, comprising an identifier of a candidate cell; 
 transmit, to a third base station, a second message to establish a connection, for the wireless device, between the first base station and the third base station, wherein the second message comprises a first identifier identifying the wireless device within the first base station; and 
 receive, from the third base station, a third message, to establish the connection, comprising a fourth identifier identifying the wireless device within the third base station. 
   
     
     
         2 . The first base station of  claim 1 , wherein the instructions further cause the first base station to receive, from the second base station, a handover request message, for a layer 1/layer 2 triggered mobility (LTM) of the wireless device, wherein the handover request message comprises:
 the identifier of the candidate cell, of the first base station, for the LTM; and   a context of the wireless device.   
     
     
         3 . The first base station of  claim 2 , wherein the instructions further cause the first base station to transmit, to the second base station, a handover request acknowledge message, for the LTM of the wireless device, comprising an LTM candidate configuration of the candidate cell. 
     
     
         4 . The first base station of  claim 1 , wherein the instructions further cause the first base station to, after the cell switch notification message:
 transmit, to the second base station, a handover success message indicating the candidate cell; and   receive, from the wireless device, a radio resource control (RRC) reconfiguration complete message.   
     
     
         5 . The first base station of  claim 4 , wherein the transmitting, to the third base station, the second message is:
 after transmitting the handover success message;   after receiving a response message for the handover success message; or   after receiving the RRC reconfiguration complete message.   
     
     
         6 . A first base station comprising:
 one or more processors; and   memory storing instructions that, when executed by the one or more processors, cause the first base station to:
 receive, from a second base station, a first message comprising an identifier identifying a wireless device within a third base station; 
 transmit, to the second base station, a handover success message indicating a candidate cell; 
 receive, from the wireless device, a radio resource control (RRC) reconfiguration complete message; and 
 transmit, to the third base station, a second message comprising the identifier. 
   
     
     
         7 . The first base station of  claim 6 , wherein the identifier identifying the wireless device within the third base station comprises at least one of:
 a first user equipment Xn application protocol identifier (UE XnAP ID); or   a second UE XnAP ID.   
     
     
         8 . The first base station of  claim 7 , wherein at least one of:
 the first UE XnAP ID is included in a first handover request acknowledge message sent by the third base station to the second base station; or   the second UE XnAP ID is included in a first handover request message sent by the second base station to the third base station.   
     
     
         9 . The first base station of  claim 6 , wherein the first message comprises at least one of:
 a fourth message received after transmitting, to the second base station, a handover request acknowledge message;   a cell switch notification message; or   a response message for the handover success message.   
     
     
         10 . The first base station of  claim 6 , wherein the first message or the second message further comprises an identifier of the third base station. 
     
     
         11 . The first base station of  claim 6 , wherein the receiving the first message is after:
 receiving, from the second base station, a handover request message, for the wireless device; and   transmitting, to the second base station, a handover request acknowledge message, for the wireless device.   
     
     
         12 . The first base station of  claim 11 , wherein:
 the handover request acknowledge message comprises a layer 1/layer 2 triggered mobility (LTM) candidate configuration of the candidate cell for an LTM; and   the handover request message comprises:
 an identifier of the candidate cell, of the first base station, for the LTM; and 
 a context of the wireless device. 
   
     
     
         13 . The first base station of  claim 10 , wherein the second message indicates a cell switch for the candidate cell of the first base station. 
     
     
         14 . The first base station of  claim 6 , wherein the identifier identifying the wireless device within the third base station is over a third interface between the second base station and the third base station. 
     
     
         15 . The first base station of  claim 6 , wherein the transmitting, to the third base station, the second message is at least one of:
 after receiving the RRC reconfiguration complete message;   after receiving, from the second base station, a cell switch notification message comprising the identifier of the candidate cell; or   to establish a connection, for the wireless device, between the first base station and the third base station.   
     
     
         16 . The first base station of  claim 15 , wherein the second message further comprises a first identifier identifying the wireless device, within the first base station, over a first interface between the first base station and the third base station. 
     
     
         17 . The first base station of  claim 16 , wherein the instructions further cause the first base station to receive, from the third base station and after the transmitting the second message, a third message, to establish the connection, comprising at least one of:
 a fourth identifier identifying the wireless device with the third base station over the first interface; or   the first identifier.   
     
     
         18 . A wireless device comprising:
 one or more processors; and   memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
 transmit, to a second base station, a measurement report message; 
 receive, from the second base station, a first radio resource control (RRC) reconfiguration message comprising a layer 1/layer 2 triggered mobility (LTM) configuration, wherein the LTM configuration comprises an LTM candidate configuration of a first candidate cell for an LTM; 
 receive, from the second base station, a cell switch command indicating the first candidate cell; 
 apply the LTM candidate configuration; 
 transmit, to a first base station of the first candidate cell, an RRC reconfiguration complete message; and 
 execute a subsequent LTM procedure for a second candidate cell, wherein a connection for the wireless device is established by a message comprising a first identifier identifying the wireless device, within the first base station. 
   
     
     
         19 . The wireless device of  claim 18 , wherein a cell switch notification message comprises an identifier of the first candidate cell. 
     
     
         20 . The wireless device of  claim 18 , wherein the executing is without a second RRC reconfiguration message.